Pellet mill die assembly



Nov. 8, 1960 Filed June 23, 1955 E. N. MEA KIN 2,958,900

PELLET MILL DIE ASSEMBLY 4 Sheets-Sheet l INVENTOR. EDGAR IV. MEA/(l/V M*z w H/S A TTOR/VEYS Nov. 8, 1960 E. N. MEAKIN PELLET MILL DIE ASSEMBLY4 Sheets-Sheet 2 Filed June 23, 1955 INVENTOR. EDGAR IV, MEAK/N MFM HISATTORNEYS Nov. 8, 1960 E. MEAKIN 2,

PELLET MILL DIE ASSEMBLY Filed-June 23, 1955 4 Sheets-Sheet 3 INVENTOR.EDGAR M MEAK/N Nov. 8, 1960 Filed June 23, 1955 E. N. MEAKIN PELLET MILLDIE ASSEMBLY 4 Sheets-Sheet 4 INVENTOR.

EDGAR IV. MEA K/IV Ms M HIS ATTORNEYS 2,958,900 Patented Nov. 58, 1960PELLET MILL DIE ASSEMBLY Edgar N. Meakin, s72 Roblar Av Hillsborough,Calif.

Filed June 23, 1955, Ser.'No. 517,627 i 7 Claims. or. 18-12) The presentinvention relates to pellet mills and more particularly to the diestructure of such mills.

Pellet mills are employed in the forming of pellets fi'om materialswhich may vary widely ,in particle size, moisture content, oil content,fibre content, particle dIS- persion and the like, all of which have amarked effect on the successful and etficient production of afirmpellet. This problem is partially. solved by designing the dies tohave special structural characteristicssuch as thickness, hole size andshape, taper. entrance, or combinations thereof, suitable for theextrusion of particular materials.

However, even such a die is not the complete answer, for a particularmaterial for which a die was initially designed, may and oftenwillchange even from hour to hour in its characteristics and to an extentwhich will cause production of soft or otherwise poor pellets. Thepreparation of separate dies to take care of such variations and thenecessary interchanging thereof in the press.

to meet the changing conditions, obviously, is impractical.

Among the objects of the present invention are;

1) To provide a novel and improved die assembly for a pellet mill;

(2) To provide a noveland improved die assembly for a pellet millcapable of being adjusted to adapt the same to extrusion of materialsvarying somewhat in character; a

(3) To provide a novel and improved die assembly which will enable theproduction of a firm pellet at good capacity despite variations in thematerial being extruded therethrough.

Additional objects of my invention will be brought out in the followingdescription of a preferredembodiment of the same taken in conjunctionwith the accompanying drawings, wherein v Figure 1 is a fragmentary viewin section, of a pellet mill of the flat die type and depicting the, dieassembly of the present invention as incorporated therein;

Figure 2 is a plan view of the die assembly of Figure 1;

Figure 3 is a view, partly in section, through a pellet mill of the ringdie type, and depicting the die assembly of the present invention asadapted for this type of mill; and

Figure 4 is a view taken in the plane 4-4 of Figure 3.

Referring to the drawings for the details of apparatus for the carryingout of my invention, the pellet mill, in general, may comprise a baseframe v1 supporting an inwardly and downwardly sloping circular bowl 3having an out-turned lower edge 5 from which a die clamp 7 such asillustrated and described in Meakin Patents Nos. 2,075,450 of March 30,1937, and 2,124,744 of July 26,

1938, is suspended to engage and support the outer edge of a dieassembly 9.

A centrally mounted sleeve 11, supported in any conventional manner inthe upper portion of the mill, carries at its lower end, as by a nut 13with a peripheral recess therein, the segments of a split ring 15 whichoffers support to the inner edge of the die-assembly.

A die block 17 carried on the nut, forms with the die assembly, thefloor of a compression chamber 19, into which the loose pellet materialis fed for extrusion through the die assembly.

Extrusion of the pellet material is accomplished through the use ofcompression means 21 involving a pair of compression rollers 23journalled in a spider 25 adapted for rotation about the sleeve as anaxis.

The upper structure of the mill, which for simplicitys sake, has notbeen illustrated, may be of any desired construction, such for exampleas is illustrated in the patent to Edgar T. Meakin No. 2,065,141 of Dec.22, 1936, or in the patent to EdgarN. Meakin No. 2,075,450 of March 30,1937. Such structure, however, is incidental to the present invention.

The die assembly 9 of the present invention, as adapted for a machine ofthe fiat die type described above, involves a die plate 27 in the formof a ring, having a plurality of extrusion tube receiving holes 29therein, each such hole being counter bored from the compression side ofthe plate to provide an enlarged entrance terminating at a shoulder 31.

Such holes are adapted to permit the assembly in the die plate, of aplurality of extrusion tubes 33 each having an enlargement at the upperend to form a head 35 adapted to fit the counter bore and seat upon theshoulder 31, whereby to withstand the extrusion pressures developed.Preferably the heads extend slightly above the surface of the die plateto assure good pressure engagement with the shoulders 31.

For about two thirds of the length of each tube, as measured from thedischarge end thereof, the tube is provided with a plurality of slits 37extending longitudinally thereof, leaving a plurality of longitudinaltube sections 39 flexibly suspended at the upper ends thereof from theunslitted portion of the tube, thereby permitting these sections to bedrawn inwardly toward the center axis of the tube until they contacteach other, or expanded outwardly therefrom. Each tube thereby becomesadjustable along the slitted portion thereof, between limits, which inone case will define a tube having its discharge end tapered and in theother case, resulting in a tube having its discharge end flared.

The tendency for the tubes to expand will be attributed to the expansionpressure of the material being extruded through the tubes. Consequenlty,to provide for adjustability of the tubes within the limits discussed,necessitates only the provision of means 41 for constricting such tubesto any degree desired within the aforementioned limits. The ultimateadjustment of the tubes, therefore, will constitute a compromise betweenthe expansive forces ,of the material being forced through the tubes andthe constricting forces caused to be exerted in opposition thereto.

Such constricting means in the preferred embodiment of the inventionunder consideration may take the form of a plurality of axially aligneddisc elements 43, 45, 47 etc., each having holes therethrough laid outon a pattern corresponding to that of the die plate, with each hole ofsufiicient diameter to loosely receive one of the tubes.

At diametrically opposite points of each disc element, extends a lug 51.These plates, preferably three in numher, are horizontally mounted on abearing 53 Which in turn is aflixed to a rod extension 55 depending fromthe sleeve 11 to which it is threadedly secured by a suitable adaptornut 57.

Of these three disc elements, the outer ones 43 and 47 are connectedtogether as a unit by a pair of hydraulic cylinders 57 each affixed to apair of corresponding lugs of these elements. Each of these cylindersincludes a piston 59 and associated piston rod 61 extending through theattached end of the cylinder, intermediate the lugs of that pair towhich the cylinder is affixed.

The intermediate disc element which may be somewhat thicker than theothers, is so adjusted angularly with respect to the outer ones as toposition each of its associated lugs in a position facing the piston rodof From this arrangement, it will be apparent that movements of thepistons will cause the outer disc elements to rotate angularly relativeto the intermediate element and that by suitable control of suchmovements, the constricting disc elements may be caused to exert aconstricting force against the split tubes. I

Such control may be effected hydraulically by including the cylinders ina hydraulic circuit, the simplest form of which may involve a pump 65having its intake or suction line 67 connected to a supply tank 69-ofliquid such as oil, and its discharge line 71 connected to the input endof each of the cylinders, while an exhaust line 73 extends from theopposite end of each of the cylinders to a return line 75 leading to thesupply tank. A bypass 77 about the pump, includes a Spring loaded valve79 which will cause the pump to exert a fixed pressure against thepistons in the system so long as the overall load on the pump, includingthe spring loading of the valve remain constant. By utilizing a springloaded valve which is adjustable, the degree to which the tubes may beconstricted while material is being extruded therethrough may be alteredto realize a desired condition in the pelleted material discharging fromsuch tubes.

Other means may be relied on for altering the'pressures and obtaining achange in the constricting forces applied to the tubes by the discelements, and While the hydraulic system specifically illustrated is ofa simple type requiring manual control of the pressure adjustments, itis contemplated that automatic means may be utilized which would respondto variations in expanding pressures attributable to any changes in thephysical characteristics of the material being extruded.

Further, while the previous embodiment of the invention has beenillustrated and described in connection with a flat plate type of pelletmill, the invention is also applicable to pellet mills of the ring dietype illustrated in Figure 3, for example.

Such type of mill, in general, involves a casing 81 having a front wall83 and a rear wall 85, each of which carries a bearing 87, 89respectively, with such bearings in alignment to receive a driven shaft91 which carries a sprocket 93 for chain connection to a source of powerin the form of an electric motor 95, for example, mounted on top of thecasing. The shaft extends to the front of the front wall, and at thatend carries extrusion means 97 which includes a pair of extrusionrollers 99.

The extrusion means is enclosed within an extrusion chamber 101,comprising in part, a ring die assembly 103 mounted along one edge, tothe front wall of the machine casing, while to the front edge of the dieassembly is affixed a conical shaped front wall 165 in the center ofwhich is an opening 107 for the introduction of the pelleting materialto the extrusion chamber.

Here again the specific construction of the mill may vary widely withinthe realm of the prior art, inasmuch as the invention is directedparticularly to the die assembly.

In this embodiment of the invention, the die assembly includes a dieplate in the form of a ring 109 having a pattern of extrusion tubereceiving holes 111 distributed thereabouts with the inner end of suchholes counter bored to receive the head ends of the extrusion tubes.

The extrusion tube constricting elements in this embodiment will takethe form of a plurality of concentric rings 113, 115, 117 etc.,preferably three in number, these being slidably supported in concentricgrooves one of the cylinders, to which rod it is coupled by a link 121,123, 125 etc., formed in the front wall of the casing, in concentricrelationship to the die plate; and are provided with radially alignedholes corresponding to the pattern of holes in the die plate, to receivethe extrusion tubes which extend radially outward from the die plate.Constricting of the tubes is accomplished by a relative angular shiftbetween the intermediate ring and the adjacent rings 113 and 117 toeither side thereof.

Such adjustment may be accomplished in a manner similar to the firstembodiment, by the mounting of diametrically disposed cylinders to theinnermost and outermost rings 113, 117, and linking the piston rod ofeach of said cylinders to the intermediate ring 115, and operating thesame hydraulically in the manner previously described in connection withthe first embodiment.

While each of the extrusion tubes may be formed integrally throughout, Iprefer to form the same of two sections, that is an upper section 127which is assembled in the die plate, and a lower section 129 which isslitted from one end. The remaining ends of the two sections havecoupling threads and are assembled by means of an internally threadedsleeve 131. The advantage of this resides in the fact that the die platemounted section may be standardized as to length, while the splitportion may be made to different lengths, so as to give to the assembledtube, characteristics which are best suited to the material to beextruded.

It will be apparent from the foregoing description of my invention, thatthe same will fulfill the objects thereof, and while I have disclosedthe same in its preferred form and in considerable detail, the inventionas thus illustrated and described is subject to alteration andmodification without. departing from the underlying principles involved,and I accordingly do not wish to be limited in my protection as to thespecific details as illustrated and described, except as may benecessitated by the appended claims.

I claim:

l. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion tube receiving holes therein, aplurality of extrusion tubes extending through said holes and supportedby said die plate, each of said extrusion tubes having a plurality ofslits extending longitudinally thereof from its discharge end, and meansfor adjustably constricting said extrusion tubes simultaneously.

2. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion tube receiving holes therein, aplurality of extrusion tubes extending through said holes and supportedby said die plate, each of said extrusion tubes having a plurality ofslits extending longitudinally thereof from its discharge end, and meansfor adjustably constricting said extrusion tubes simultaneously, saidmeans including a plurality of constricting elements, and means forsimultaneously moving said constricting elements in relatively oppositedirections.

3. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion tube receiving holes therein, aplurality of extrusion tubes extending through said holes and supportedby said die plate, each of said extrusion tubes having a plurality ofslits extending longitudinally thereof from its discharge end, and meansfor adjustably constricting said extrusion tubes simultaneously, saidmeans including adjacently disposed constricting elements, each having aplurality of holes through which the slitted portions, of said tubespass, and means symmetrically coupled to said constricting elements formoving said elements in relatively opposite directions to imposeconstricting force on said extrusion tubes simultaneously. V V

4. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion 'tube receiving holes therein, aplurality of extrusion tubes extending through said holes and supportedby said di'e plate, each of said extrusion tubes having a plurality ofslits extending longitudinally thereof from its discharge end, and meansfor adjustably constricting said extrusion tubes simultaneously, saidmeans including adjacently disposed constricting elements, each having aplurality of holes through which the slitted portions of said tubespass, and means coupled to said constricting elements for angularlyrotating said elements in relatively opposite directions to imposeconstricting force on said extrusion tubes simultaneously.

5. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion tube receiving holes therein and acounterbore at each hole, a plurality of extrusion tubes each having ahead end adapted to fit a counterbore, said tubes extending through saidholes and with their head ends in said counterbore, each of saidextrusion tubes also having a plurality of slits extendinglongitudinally thereof from its discharge end, and means for adjustablyconstricting said extrusion tubes simultaneously, said means including aplurality of adjacently disposed constricting elements, each having aplurality of holes through which the slitted portions of said tubespass, and means coupled to said constricting elements for moving saidelements in relatively opposite directions to impose constricting forceon said extrusion tubes simultaneously.

6. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion tube receiving holes therein and acounterbore at each hole, a plurality of extrusion tubes each having ahead end adapted to fit a counterbore, said tubes extending through saidholes and with their head ends in said counterbores, each of saidextrusion tubes also having a plurality of slits extendinglongitudinally thereof from its discharge end, and means for adjustablyconstricting said extrusion tubes simultaneously, said means including aplurality of adjacently disposed disc elements, each having a pluralityof holes through which the slitted portions of said tubes pass, andhydraulic means coupled to said disc elements at diametrically locatedpositions for angularly rotating adjacent ones of said disc elements inrelatively opposite directions to impose constricting force on saidextrusion tubes simultaneously.

7. A die assembly for a pellet mill or the like comprising a die platehaving a plurality of extrusion tube receiving holes therein, aplurality of extrusion tubes extending through said holes and supportedby said die plate, each of said extrusion tubes including an uppercylindrical section and a lower cylindrical section coupled thereto andhaving a plurality of slits extending longitudinally thereof from itsdischarge end, and means for adjustably constricting said extrusiontubes simultaneously, said means including a plurality of adjacentlydisposed constricting elements, each having a plurality of holes throughwhich the slitted portions of said tubes pass, and means coupled to saidconstricting elements for angularly rotating adjacent ones of saidelements in relatively opposite directions to impose constricting forceon said extrusion tubes simultaneously.

References Cited in the file of this patent UNITED STATES PATENTS2,432,326 Meakin Dec. 9, 1947 FOREIGN PATENTS 918,288 France Oct. 14,1946 972,080 France Aug. 23, 1950

